327carguy

This post will be a little long and I will follow it with photos. I was swapping out my pumpkin (gears) with a replacement pumpkin that is a date correct 3:36 posi. It was to replace a 4:56 posi from a much later vehicle. I wanted to rebuild the replacement before the install.

The posi is dated Dec 57 going in a January 1958 Vette. This is a four disk posi with right hand threads. Upon disassembly we found broken parts in the clutch pack and the Bellville disk were warped as opposed to concaved.

We ordered a clutch pack from a major Corvette Vendor. After 6 weeks of back order the parts arrived. When we went to reassemble, the splined clutch disks were so small they would not fit over the splines on the posi gears. The originals had a 3.7 inches outside diameter and the interior diameter was 2.0” and 2.2” at the inside of the splines (bottom of tooth, top of tooth). The new clutch disks were a good 3/16” smaller in outside diameter and the inside diameter was cut for 1.8 and 2.0 at the splines.

Of course we returned the parts for the correct parts only to be told the vendor’s parts were correct and I must have some Rube Goldberg posi unit. The Vendor is sending the wrong non fitting parts back to us. I of course would prefer a credit.

In the meantime we tried to assemble the unit using the old clutch disks and the new Bellville disks. When assembled the unit appears to be extremely tight. I’m concerned the Bellville disks have too much arch to them. They measure 0.20” each. No way to tell what the original Bellville was because it is warped and almost flat.

If anyone has run across a similar problem please advise.

Thanks in advance for any help you can provide.
Please give me a few minutes to post the photos.
Pete aka 327carguy

327carguy

first set of photos

327carguy

Second set of photos. Hoping not to get timed out

327carguy

Again any help will be appreciated.

Pete

Plasticman

I have 2 sets of Spicer discs that measure identical to yours (as shown in your pictures), that I purchased from Car Quest a few years back (as recommended by Tom Parsons - DZAUTO here on the forum).

The boxes are marked Spicer PL & Disc Kit, p/n 22233X, and are for my 62 Vette.

Each kit box contains 6 "tang" discs, and 4 "splined" discs. 2 of the tang discs are Bellville in each kit, with the other 4 tang discs flat. However, I just noticed that one kit box had 4 of the flat tang discs all being the same thickness, while the other kit box (same markings) has 2 thin machined flat tang discs and 2 thick (same thickness as the other kit).

Hope this helps, and hopefully Tom will "step in".
Plasticman

327carguy

I don't know when they switched from a four disk to a five disk pack.
I know the early ones like mine are four disk two Bellville, two flat tang disk and four splined disk. The center section has right hand threads. I was told the five disk pack have left hand threads. However, I don't have first hand knowledge of that.

I did find your answer helpful and will check out Car Quest. Are they a national parts house?

Thanks Pete

DZAUTO

Where are pictures of the wrong parts?

327carguy

The splined disks were sent back because they were too small and would not fit the splines on the gears. The vendor said they are not wrong and has put them back in the mail to us. When they arrive again I will photo and add to the thread. They just look like a smaller version and have the correct amount of teeth.

Pete

DZAUTO

The pictures of the discs/plates that you posted----------------------ARE THE CORRECT STYLE PARTS, PERIOD!


Those posi units were made for GM by DANA. They were used in 57-62 Corvettes and 57-64 pass cars.
The early units (57-59) use 8 plates/discs (4 per side). ORIGINALLY, the early units DID NOT, repeat, DID NOT use a Belleville plate. ALLLLLLLLLLLLLLLLL the plates/discs were flat and the same thickness.
In 1960, the posi units were upgraded and some changes were made. The 60-64 posi units got 10 plates/discs (5 per side) with ONE Belleville plate on each side---------------------AND ONE THIN, FLAT PLATE PER SIDE.

An early unit (57-59) which uses 8 plates/discs can be upgraded (and it's good to do it) by REPLACING a flat plate with a Belleville plate on each side.

WHEN FRESHLY REBUILT WITH NEW BELLEVILLE PLATES, THEY SHOULD BE TIGHT!!!!!!!!!!!!!!!
Actually, with an axle stuck in each side, it should be nearly impossible to hold one axle and turn the other axle by hand. That's how tight they should be. With age and miles on the plates, there should still be good resistance to turning one side while holding the other side.

MANY, MANY years ago, the DANA replacement clutches, as well as DANA clutches that were re-boxed and sold by Chevy parts depts, had TWO Belleville plates and TWO Belleville discs------------------that REALLY made a posi tight!!! Those DANA boxes were 22719X. They did include 2 thin plates.
LATER DANA clutch packs, 22233X, only included 2 Belleville plates and NO thin plates. ALLLLLLLLLLLLLLLL plates/discs were the same thickness. Thus, it was necessary to EITHER use the old thin plate, OR, take a thick plate to a machine shop and have it surfaced to about .060 thickness (which is what the aftermarket vendors were doing).

This is a DANA clutch pack, RE-BOXED by GM and sold over the parts counter.



This is the early DANA clutch pack (22719X) which contained 10 plates/discs ( 2-thick flat plates, 2-Belleville plates, 2-thin flat plates, 2 flat discs, 2-Belleville discs).


This is the later DANA clutch pack which had 2 Belleville plates and ALL plates/discs were the same thickness. AGAIN, it is necessary to NOT USE one of the thick plates. EITHER re-use the old thin plate, OR, have a thick plate surfaced down to .060 thickness (I have this done to old, used thick plates).


Now, with all of that said, lets dwell on the posi unit specifics.
FIRST, and foremost, MOST, read again, MOST of the early and late posi unit parts CANNOT BE INTERCHANGED!!!!! A complete posi unit (early or late) can be used interchangeably, but the individual parts CANNOT BE SWAPPED!
The 2 case halves, the cross shafts, axle gears and spider gears are different between early and late units. ONLY, ONLY, ONLY the ring which mates to the clutch disc is the same between early/late units.
Early/late spider and axle gears have different teeth and to not properly mesh with each other.
The V in the case halves/cross shafts are at different angles between early/late units, thus, they don't mate the same. The change in the angles was a result of the change in the clutch pack and the preload on the clutch pack resulting from the Belleville plates.

Here is a comparrison between early(left) and late cases. Notice the difference in the Vs.



Early cases have RIGHT HAND, COARSE thread bolts.
Late cases have LEFT HAND FINE thread bolts.
All bolts were grade 8.

COMPATABLE, LEFT HAND THREAD BOLTS ARE AVAILABLE FROM ARP AND ARE SPECIFIED FOR THE CHRYSLER POSI UNITS-------------THEY ARE THE SAME.

327carguy

Thank you Tom. That was the best answer ever. I now know the Corvette vendor has the wrong parts. PERIOD.

The information on the Bellville was great. I now believe my warped Bellville may have started life flat.

Many thanks Pete

DZAUTO

PETE,
Re-read my information-------------I edited some errors.

Plasticman

Pete,

Car Quest is in Chicago area and Florida, but don't know about other areas. Can order parts "online":

http://www.carquest.com/

John (Plasticman)

327carguy

Tom, just to clarify the quote below. Are you saying the earlier posi unit with four disks per side should have one disk surfaced to 0.060 when using the Bellville or was that referring to the five disk posis?

DZAUTO

Pete,
The early units (57-59) use 8 plates/discs that are ALLLLLLL the same thickness.
When ORIGINALLY built, all 8 plates/discs were FLAT. BUT, they can be updated to grip better and faster by simply replacing one of the flat plates (the ones with 4 tabs) with a Belleville plate.
ONLY the later (60-64) posi units used one thin plate. If you attempt to use 10 plates/discs that are the thick version in them, the posi cases will be over stressed and the plates/discs will chew themselves up.
SOOOOOOOOOOOOOOOO, early units, 8 Thick plates/discs------late units, 8 thick plates/discs, 2 thin (flat) plates.

For the early units, if you prefer to replace a thick plate with a Belleville plate, the arrangement should be:
Disc-Belleville plate-disc-plate on each side.
The disc goes to the OUTSIDE, the plate goes to the inside.

327carguy

Tom, Thank again. Excellent help.

Pete